Running too warm

[mhsprecher]

I will try and keep this to the point, but my 28 roadster has been running too hot. When I first got it, no problem. I changed the points and then had a condenser fail. When I replaced the steel fan with an aluminum one, I noticed that the area on the water pump where the front grease fitting screwed in was broken. I had a spare water pump, so I put that in. Since that time the car has run hotter than I like, 190+ degrees.

I had a club technical guru come and help me time it, so it is pretty much on the money. Carb is adjusted properly. It starts right up and runs great.

Depending upon the weather, the temp in the radiator, measured with an infra red gun, is around 195 and sometimes lower. On Sunday, while coming back from a cruise-in, the temp reading on the motometer got almost to the top. I was ready so pull over when the temp started dropping and probably was 175 or so not much later. Outside temp was in the 80s. Yesterday, after a 6 or 7 mile drive, it was in the 195+ range. I did readings on the radiator itself. The top: 190s, down passenger side, 190s, bottom 183 average.

After the timing and carb adjustment I did a vinegar flush. I flushed it 5 or 6 more times, including a Simple Green flush. The water is still coming out pretty murky, so I was thinking of doing another vinegar flush today and continuing to flush until it runs clear.

I bought the car in the spring. It had not run much. It had good antifreeze in it at the time. I wish that I had driven it more after each little change I made in order to determine whether any one of my "improvements" had made the difference. Reminds me of the "if it ain't broke, don't fix it" school of thought. I probably didn't need to replace the points. Condenser might or might not have failed after that. Maybe the old water pump was good enough? I put one of those collars on the pump shaft to keep it from moving.

What is the collective wisdom here? My sense is that maybe the water pump replacement stirred up some rust and I am not getting the heat transfer I need? Maybe the new pump is working too well and I am getting too much flow and not enough time to dissipate the heat from the coolant? Is it due to the warmer outside temperatures this summer? I did send a note to the prior owner and he had no "overheating" problems. My 1930 town sedan runs cool, so seeing so much red on the motometer makes me nervous.

[Gunmetal blue2]

Do you have a therostat in the car, if yes it is probly a 180 you will need a 160. I would go with your last answer that the water is going throu to fast not giving the coolant enough time to cool the water down. A lot of guys on here have ground off parts of the empellers to slow down the water flow. Do a search on here and you should find articales on that subject. Good Luck.

[Greg Jones]

I'd also check for a thermostat in upper hose.

[eagle]

As far as the "water flowing too fast to cool" theory, that is complete bosh. However, a cavitating impeller will cause REDUCED flow, and that will be a problem. Compare your old impeller to your new one and see if there is a difference. Is the car boiling? If not then leave it be. 195 is fine, you would have to be at a pretty high elevation to boil at that temp. Over 9000 feet if my math is correct...

[mhsprecher]

I do not have a thermostat. I have not done anything to the impeller and it looks pretty much the same as the one I took out. It seems odd that the temp would fluctuate so much.

[700rpm]

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I struggled with overheating in my coupe and tried all the remedies you tried, to no avail. I finally pulled the engine (for other reasons) and had the block and head boiled out. In spite of all my previous efforts, they were both clogged with rust. Only boiling and beading cleaned them completely, and upon reinstallation, no more overheating. I have become convinced that many heating problems are caused by rust buildup in the water jackets. Some guys here have had great results eliminating that buildup with Evapo-Rust, which, unlike boiling, doesn't harm babbitt. You might try that.
Also, radiators are often clogged more than you might expect. I can't remember the exact figure, but someone here once said that as a quick flow test, your radiator ought to completely drain in something like less than minute (?)* when the lower hose is detached. Unless you are absolutely certain your radiator is flowing properly, pull it and have it rodded. I say rodded, because boiling doesn't always work because of variations in methods at different shops.
These are more involved solutions to the overheating problem, but if you've got your timing and other related issues covered, I think these are the next steps.

* tbird clarified this as 4 seconds (below).

[mhsprecher]

Thanks, 700 RPM. My next step is to have the radiator rodded. I will try Evaporust, too.

[tbirdtbird]

sounds like clogged rad. Chemical cleaning only gets you just so far.
Should be a 30* temp drop from top of rad to bottom

Pull hoses from rad. Block off upper inlet. stuff rubber ball in lower outlet. Fill with water. Remove ball. Rad. should empty in 4 seconds. If longer it is clogged. Old old trick. I am quoting from Bratton's

[mhsprecher]

Thanks, Tbird.

[TinCup]

When I was chasing my own overheating issues I found that typically if the top of the radiator was reading 190 that at the bottom hose it should be around 150 to 160. You are only showing a 10 degree drop from the top to the bottom. Sounds like clogged radiator to me.

[stewwolfe]

Jack Bahm has a YouTube video on flow testing a Model A radiator. Do a search for it in You Tube.